1. Field of the Invention
The present invention relates to an extension for a wrench and, more particularly, to an extension reliably and releasably coupled to an end of a handle of a wrench.
2. The Prior Arts
Wrenches with a short handle are more useful than wrenches with a long handle in small spaces but provide small torque. To save costs, an extension is attached to the short handle of the wrench to increase the arm of force, and the extension can be detached to allow use of the wrench in a small space. FIG. 1 shows a conventional arrangement for coupling an extension 50 to an end 33 of a handle 32 of a wrench 30. Wrench 30 includes a head 31 with a drive portion 34 for driving a fastener. End 33 includes a receptacle 331 receiving an engaging device 40 comprised of a positioning member 41 and a spring 42. Positioning member 41 includes a larger section and a smaller section 411 having an outer diameter smaller than that of the larger section that is slideably received in receptacle 331. Extension 50 includes a tubular member 51 having an engaging portion 52 with a positioning hole 521. End 33 of handle 32 is inserted into tubular member 51. Spring 42 biases the smaller section of positioning member 41 into positioning hole 521 of tubular member 51 to position end 33 of handle 32 in tubular member 51. To allow easy coupling between tubular member 51 and handle 32, a spacing A (FIG. 2) must be provided between end 33 of handle 32 and an inner periphery of tubular member 51. However, end 33 of handle 32 wobbles in tubular member 51 due to the existence of spacing A. Furthermore, spacing A becomes larger after a period of time of use, leading to undesired disengagement of positioning member 41 from positioning hole 521.
Thus, a need exists for an extension that can be reliably and releasably coupled to an end of a handle of a wrench to increase the arm of force.